Building a Product, Vendor and Product IDs

Chapter 4 Software Development

with the above-mentioned requirement for average suspend current.

4-3-5. Building a Product

Generally speaking, building a product with the help of the JOB60851 board requires the following modifications and additions to the software.

(1)Adding and modifying descriptors

At the minimum, the source code has to provide vendor and product IDs. (See Section 4.3.6 below.) Descriptors generally also have to be modified to reflect the final product, application, and device class.

(2)Adding to class specifications

Building a product in a certain class involves adding requests specified by the class specifications and descriptors required by the class. Some classes even require additions and modifications to the standard descriptors.

(3)Adding vendor-specific specifications

Vendor-specific requests implement the control commands and control protocols unique to that vendor. The vendor must also add descriptors that the host can access with GET_DESCRIPTOR requests.

(4)Developing application layer

Here the developer writes an application layer program combining API functions and callback functions.

(5)Tuning data flow

The flexibility of modification that the sample firmware provides through highly generalized programming sometimes comes at the expense of efficiency. Although maximizing system throughput involves looking at more than just firmware, there are places where the source code should be rewritten for speed--to use unidirectional endpoints, for example.

4-3-6. Vendor and Product IDs

Each USB product requires two numbers to uniquely identify it to the host operating system for use in selecting drivers: a VendorID assigned by the USB Implementers Forum and a ProductId chosen by the vendor. The sample firmware uses those for Oki Semiconductor and the JOB60851 Starter Kit, respectively. These may be safely used through the prototype stage. Shipping products, however, must have their own.

The following URL links to the procedure for acquiring a VendorID from the USB Implementers Forum.

http://www.usb.org/developers/

4-3-7. Other Tools Necessary

(1)Bus monitor

The sample firmware will not necessarily work perfectly when first ported to a new microcontroller because of the differences in microcontrollers and compilers. An extremely effective way to thoroughly check the operation of such a port is with a bus monitor tracing actual traffic on the bus.

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